This application claims the priority of 198 16 329.0-16, filed Apr. 11, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a heating or air-conditioning system for vehicles, and more particularly, to a system for controlling the position of a closing member to control the flow of conditioned air.
In the case of a known heating or air-conditioning system for motor vehicles of this type, such as German Patent Document DE 31 51 263 A1, the warm-air inflow opening of an air mixing chamber is arranged on the side of the heat exchanger which is forward in the air current, on the heat exchanger air inlet surface. The cold-air inflow opening is arranged to be inclined thereto at approximately an acute angle larger than 60xc2x0. Both inflow openings are controlled by a single swivellably arranged air flap which, in one of the respective two swivelling end positions, alternately completely shuts off the cold-air inflow opening and the warm-air inflow opening. The control device for controlling the air flap and the shut-off valve has an operating lever which is non-rotatably disposed on the swivel shaft of the air flap, as well as a swivelling lever which is non-rotatably connected with the shaft of the stop valve of the shut-off valve. On the swivelling lever, a circularly bent sliding surface is constructed on which the operating lever slides with its free end, at the end of the sliding surface, a projection protruding over this sliding surface.
In this type of arrangement when the air flap is in one swivelling end position, in which it completely covers the cold-air inflow opening, the shut-off valve is open and the heating or air-conditioning system heats maximally. When the air flap is moved toward its other swivelling end position, which can take place either manually or by means of a motor, the cold-air inflow opening is increasingly opened and cold air is increasingly added to the warm air in the air mixing chamber until a desired mixed-air temperature is reached. When the air flap is swivelled, the free end of the operating lever slides along the circular-arc-shaped sliding surface without operating the swivelling lever. When the air flap is changed into the other swivelling end position, in which the warm air flow opening is completely shut off, shortly before this swivelling end position is reached, the operating lever impacts on a projection and displaces it, whereby the swivelling lever is swivelled and, as a result, the stop valve of the shut-off valve is rotated into the closing position. The shut-off valve is closed and the warm-air inflow opening is completely covered so that no more air can pass through the heat exchanger and the complete air flow reaches the air mixing chamber by way of the cold-air inflow opening. The heating or air-conditioning system is set to maximal cooling with fresh air or with fan air cooled by means of an evaporator. The described arrangement of the air flap in front of the air inlet surface of the heat exchanger requires either a large air duct cross-section in front of the head exchanger and thus a large-volume climatic box or results in an unfavorable flow against the heat exchanger and thus a high flow resistance in the flow duct during the heating operation.
In the case of another known air conditioner for motor vehicles as disclosed in German Patent Document DE 35 26 518 C2, the control system has a computer which controls a water operating device as well as an air flap arranged in front of the heat exchanger. The air flap is again designed such that, in one swivelling end position, it completely covers the cold-air inflow opening and, in another swivelling end position, it completely covers the warm-air inflow opening and thus the whole air passage surface of the heat exchanger. In the xe2x80x9cmaximal coolingxe2x80x9d position of the air conditioner, in addition to the covering of the warm-air inflow opening, an additional flap is triggered such that a bypass around the air mixing chamber is opened and thus the air resistance in the flow duct is lowered.
It is an object of the invention to provide a heating or air-conditioning system of the above-described type, wherein the flow duct produces low flow resistance offers to the air flow in all operating modes and which permits a compact construction of the air guiding or climatic box accommodating the flow duct.
In the case of a heating or air-conditioning system of the type indicated in the attached claims, this object is achieved according to the invention wherein the warm-air inflow opening controlled by the closing member is arranged behind the heat exchanger. The control system is designed such that following closure of a shut-off valve, the control system changes the closing member into an open position to completely open the warm-air inflow opening.
The heating or air-conditioning system according to the invention has the advantage that, as the result of the arrangement of the warm-air inflow opening of the air mixing chamber behind the air outlet surface of the heat exchanger, a straight-line flow against and through the heat exchanger is achieved without any diversion or deflection of the air flow, so that the internal flow resistance of the system is low. In addition, in the maximum cooling operation, by opening up the warm-air inflow opening after the closing of the shut-off valve for the heating medium, the cold air is guided not only via the cold-air inflow opening but, in addition, also through the cold heat exchanger by way of the warm-air inflow opening. As a result, in this operating phase, wherein a very high air flow rate is desired, the inflow cross-section available for the flow into the air mixing chamber is considerably reduced, whereby the flow resistance is lowered. This reduces noise generation and the fan for producing the air flow can also be operated at low rotational speeds, which again results in a reduction of noise.
Advantageous embodiments of the heating or air-conditioning system according to the invention with expedient further developments of the invention are contained in the additional claims.